Vehicle direction correcting apparatus

Abstract

A vehicle direction correcting apparatus comprises: a first filter for passing therethrough a low frequency component contained in the output voltage of a relative direction detecting unit to thereby produce a first output voltage; a second filter having delay time different from that of the first filter, for passing therethrough a low frequency component contained in the output voltage of the relative direction detecting unit to thereby produce a second output voltage; a voltage judging unit for judging as to whether or not the first output voltage of the first filter is made coincident with the second output voltage of the second filter within a predetermined error range; and a control unit for setting an output voltage of the relative direction detecting unit as the central point potential in the case that the voltage judging unit judges that the first output voltage is made coincident with the second output voltage within the predetermined error range. As a result, the vehicle direction correcting apparatus can correct the output voltage of the relative direction detecting unit based upon this central point potential in the output voltage of the relative direction detecting unit for detecting direction of the vehicle in such a manner that the drift error contained in the output voltage is eliminated.

What is claimed is: 
     
       1. A vehicle direction correcting apparatus for correcting an output voltage of relative direction detecting means based upon a central point potential in the output voltage of said relative direction detecting means for detecting direction of a vehicle in such a manner that a drift error contained in said output voltage is eliminated, said apparatus comprising: first filter means for passing therethrough a low frequency component contained in the output voltage of said relative direction detecting means to thereby produce a first output voltage;   second filter means having delay time different from that of said first filter means, for passing therethrough a low frequency component contained in the output voltage of said relative direction detecting means to thereby produce a second output voltage;   voltage judging means for judging as to whether or not said first output voltage of the first filter means is made coincident with said second output voltage of the second filter means within a predetermined error range; and   control means for setting an output voltage of said relative direction detecting means as the central point potential in the case that said voltage judging means judges that said first output voltage is made coincident with said second output voltage within said predetermined error range.   
     
     
       2. A vehicle direction correcting apparatus as claimed in claim 1, wherein said control means sets an output voltage of said relative direction detecting means as the central point potential in the case that said voltage judging means continuously judges that said first output voltage is made coincident with said second output voltage within said predetermined error range during a time duration longer than predetermined time. 
     
     
       3. A vehicle direction correcting apparatus as claimed in claim 2, wherein said voltage judging means calculates a difference between said first output voltage and said second output voltage, and judges as to whether or not said difference exceeds a preselected value. 
     
     
       4. A vehicle direction correcting apparatus as claimed in claim 3 wherein said control means includes means for latching the output voltage of said relative direction detecting means. 
     
     
       5. A vehicle direction correcting apparatus as claimed in claim 1, wherein control means sets an output voltage of said relative direction detecting means as the central point potential in the case that said voltage judging means judges that said first output voltage is made coincident with said second output voltage within said predetermined error range, and also sets an output voltage of said relative direction detecting means as the central point potential, which is acquired immediately before such a judgment, in the case that said first output voltage is not made coincident with said second output voltage within said predetermined error range. 
     
     
       6. A vehicle direction correcting apparatus as claimed in claim 5, wherein said voltage judging means calculates a difference between said first output voltage and said second output voltage, and judges as to whether or not said difference exceeds a preselected value. 
     
     
       7. A vehicle direction correcting apparatus as claimed in claim 6, wherein said control means includes means for latching the output voltage of said relative direction detecting means. 
     
     
       8. A vehicle direction correcting apparatus as claimed in claim 1, wherein said voltage judging means calculates a difference between said first output voltage and said second output voltage, and judges as to whether or not said difference exceeds a preselected value. 
     
     
       9. A vehicle direction correcting apparatus as claimed in claim 8 wherein said control means includes means for latching the output voltage of said relative direction detecting means.